[Lizard]

Modifying the stencil won't affect shapes used from it. But there is a way to update all the objects of a certain type at once.
The canvas inspector has a selection tab. This will show you all the different types of objects in your document. For example, it might say you have 8 green circles and 4 blue squares. If you click on the green circle icon, it will select all the green circles in your document. Then you can use the other inspectors to adjust their properties (color, dimensions, line weight, etc.) Hope this helps.